A survey of corneal curvature changes from corneal lens wear

摘要: The fact that variations in corneal curvature occur as a result os wearing PMMA contact lenses has been reported many times (1-8). nature of these changes and the factors influencing them are, however, still not well defined. Estimates frequency lens wearers vary from 24% (9) TO 100% (5) with full range intermediate values. Similar uncertainty is evident findings on extent direction changes. Values for magnitude change zero to 2.25D (10) while up 6.00D aastigmatism have reported.(11,12)With regard fo change, th most commonly expressed view early contat literature was mold its own shape. (13-18) A flat would flatten apical curve, steep steepen curvature, all cases reduction astigmatism result. Reports surveys keratometric give only partial support molding hypothesis (1-9). They show are more complex than simple since fitted any particular way can produce either steepening or flattening, an increase decrease astigmatism. there several reasons this describing variation. studies used different types lenses, particularly fitting relationship cornea, both measurement differ study study. As well, criteria presence used. Analysis tthe results further confused by universal difficulty adequately influence variables made harder ascertain because ommission some relevant information almost studies.